1. Field of the Invention
The present invention relates to an ink cartridge for use in an inkjet recording apparatus for recording images, characters, and the like on recording paper by ejecting ink droplets from a nozzle, and to a residual amount display method of ink of the ink cartridge.
2. Description of the Related Art
Currently, there are provided in various kinds ink jet printers for recording images, characters and the like by ejecting ink droplets on a recording medium, such as recording paper. In the ink jet printer, ink is supplied from an ink cartridge to a recording head through an ink supply tube, and the ink droplets are ejected from a nozzle of the recording head onto the recording paper, thereby performing recording.
Further, generally, in an ink cartridge used for an ink jet printer, an ink bag in which ink is sealed in advance is accommodated in a casing. The ink bag is configured to have flexibility and deform according to the ink residual amount so that the thickness thereof changes. Then, the ink residual amount is estimated by measuring the thickness of the ink bag. This is because the ink residual amount cannot be directly measured.
For example, Japanese Patent Application Laid-Open No. 2007-268721 describes an ink cartridge capable of detecting the residual amount. In the ink cartridge, a housing of the ink cartridge is stuck to one surface of the ink bag, and a plate is stuck to the other surface so that the plate can move according to the ink residual amount. Thus, by detecting a state where the plate arrives at a position corresponding to the ink residual amount of “zero”, it is possible to detect a state where the ink is used up.
The plate includes a pin protruding toward the side surface of the housing, which pin is inserted into a rotatable lever portion that can slidably move on the side surface of the housing. The lever portion is provided with a nonreflective plate. The housing has an opening, where a reflecting plate is arranged at a back of the opening. The plate moves according to a volume of the ink, and the lever portion rotates by the pin.
In a case where the ink has not been consumed, the lever portion is not positioned between the reflecting plate and a window, and the light entering the window is reflected by the reflecting plate. In a case where the ink has been consumed, the lever portion is positioned between the reflecting plate and the window, and the light entering the window is not reflected by the nonreflective plate. Thus an ink cartridge is provided in which the ink residual amount can be recognized by detecting the state of the reflected light.
However, the conventional ink cartridge still has the following problems to be solved.
In the conventional ink cartridge, the pin formed in the plate moves by expansion and contraction of the ink bag. Additionally, a proximal end of the lever portion is engaged with the housing, and the lever portion rotates so that a distal end thereof draws a circular arc. A guide groove having a long hole-shape along a length direction of the lever portion is provided at the distal end of the lever portion, and the pin is inserted into such guide groove. A guide member is provided at the side surface of the housing so that the distal end of the lever portion slidably moves on the side surface of the housing. According to such structure, the movement of the pin is regulated to the track of the guide groove of the lever portion.
The pin moves three-dimensionally in accordance with the movement of the ink bag because the pin is formed at the plate fixed to the ink bag. The ink bag does not perform a regular movement every time, and performs different movements every time depending on the installed situation, usage frequency, and the like. Thus, the lever portion regulating the movement of the pin is applied with force according to the movement of the pin. Problems do not arise if the pin performs a linear movement in a thickness direction of the ink bag according to expansion and the contraction of the ink bag, but in other cases, the ink residual amount may not be correctly indicated if the pin applies force in various directions to the lever portion. Further, another problem arises in that the lever portion may become hard to move due to friction with the side surface, and hence the ink residual amount may not be correctly displayed.